This invention generally relates to press-on/pry-off closures and, more particularly, to composite press-on/pry-off closures having a removal assist feature as well as to methods of making the same. In this regard, an important aspect of the present invention is directed to an improved press-off/pry-off composite closure which is especially suited for use with containers having a beaded finish which closure is formed by top-side insertion of a metal end panel into an injection molded rim composed of a flexible plastic such as a thermoplastic polyolefin wherein the rim includes a thumb engageable removal-assist tab.
When press-on/pry-off closures are removed from containers, particularly those which have been closed under vacuum, a larger than normal force is required to break the vacuum to move the closure. This force, in addition to the interlock between the closure skirt and the container neck finish, is dependent upon closure size and vacuum level. Accordingly, it is desirable to provide effective removal-assist features for such closures, particularly where they are applied to packaged products which have a high degree of fluidity and are thus susceptible to spillage.
Press-on/pry-off composite closures having removal-assist features are well known in the prior art and have been commonly used for a wide variety of products including hot fill and cool products as well as for closed retorted products. For example, U.S. Pat. No. 4,423,822 which issued to Continental White Cap, Inc. describes a press-on/pry-off closure that is provided with a thumb engageable tab formed within the skirt that aids in the removal of the closure from a container to which it is applied. That closure, while highly satisfactory for commercial use by packers and consumers, includes a construction which requires that the end panel be inserted into the bottom-side of a preformed flexible plastic rim and, as such, is characterized by component manufacturing and assembly steps which are relatively complex and costly. For example, the plastic rims of such closure have a sidewall design which require relatively large undercuts for facilitating removal from the injection mold. Correspondingly, the forces necessary to insert the end panel past the lugs make assembly more relatively difficult and require the use of heavier and/or more rigid end panels.
The present invention is an improvement over the aforementioned press-on/pry-off composite closures and provides a novel press-on/pry-off composite closure formed of a top-side inserted metal end panel and flexible plastic rim having a thumb engageable removal-assist tab. This rim includes an annular skirt having an interior surface that is provided with a ledge for receiving and supporting the end panel, a plurality of container bead-engageable lugs below that ledge and a plurality of panel-retaining flexible formations adjacent an upper edge of the rim. The lugs extend radially inwardly a distance greater than the radial-inward extent of both the ledge and the panel-retaining flexible formations. Insertion of the end panel into the top side of the rim is enabled by the sizing and construction of the panel-retaining formations which are axially spaced from the ledge to define an end panel-engaging segment in the rim which is sized to snugly receive and secure the end panel.
The thumb-engageable tab is integrally formed with the rim and positioned below the upper edge of the rim. A hinge portion at the upper end of the tab enables it to be outwardly pivoted to thereby apply a lifting force to the rim when the closure is on a container. If desired, the side portions of the tab can be joined to the remainder of the skirt portion by relatively thin membranes which either permanently deform or fracture when the tab is actuated.
It is, therefore, a general object of the present invention to provide a new and improved composite press-on/pry-off closure having a top-side inserted end panel which is captured within a surrounding plastic rim having a skirt portion that includes a thumb-engageable pivotable tab for applying a lifting force to the rim to facilitate removal of the closure from a container to which is it applied.
Another object of the present invention is to provide an improved press-on/pry-off composite closure having a top side inserted metal end panel surrounded by a plastic skirt having a construction which permits the use of a metal end panel having an outer periphery which is curled to provide a concealed raw cut-edge.
Another object of the present invention is to provide a novel and improved method of forming a press-on/pry-off composite closure.
Another object of the present invention is to provide an improved press-on/pry-off composite closure having a metal end panel and seal area characterized by improved plastic sidewall rim protection of the end panel, enabling the closure to withstand greater impact abuse.
Another object of the present invention is to provide an improved press-on/pry-off composite metal closure having a metal end panel surrounded by a plastic rim having a sidewall skirt which tapers inwardly from the top portion of the skirt to the bottom portion thereof, thereby minimizing if not totally eliminating the possibility of the sidewall skirt coming into contact with shipping container dividers and the like and avoiding inadvertent and/or unintentional removal of the closure from a container to which it is applied.
Another object of the present invention is to provide an improved press-on/pry-off composite closure having a thumb engageable removal assist tab which provides visual evidence of tampering.